Antifreeze, danger

Ethylene glycol is common in automotive antifreeze mixtures. Because of its toxicity, it is sometimes replaced by propylene glycol, which is FDA approved for use in food, and is considered generally accepted as safe. Ethylene glycol has a sweet taste, and accidental poisoning in children is a danger. 

Alcohols. Methyl alcohol, and to a lesser extent ethyl alcohol, were used as freezing point depressants for many years. Their use now is minimal. When properly inhibited, alcohol-water solutions can be satisfactory coolants only under restricted conditions. Alcohol antifreezes fell into disuse because of their low boiling point (lower than that of water) and the danger of loss from boiling or evaporation. Alcohol volatilizes from hot surfaces much more readily than glycol coolant and can be a potential fire hazard. Methyl alcohol liquids are both flammable and poisonous. Methyl alcohol vapors are toxic when inhaled at high concentrations. 

Ethylene glycol has a characteristically sweet smell that makes it irresistible to animals. The bright green or red fluorescein dye is added to warn humans and animals of the inherent danger associated with the ingestion of antifreeze. If antifreeze is swallowed, it causes central nervous system depression followed by respiratory and cardiac distress. If untreated, ingestion leads to cardiac failure, renal failure, and brain damage. 

It is not necessary to possess chemistry glassware to distill antifreeze. The stuff is not corrosive, or otherwise particularly dangerous (so long as it is not drunk, or the hot fumes sniffed ) so a homemade still can be constructed and used for the process with good results so long as care is taken in its construction and use. A workable still can be built along the lines shown in the drawing below ... 

Sense of Danger Our sense of taste can detect certain toxins found naturally in plants. Research other modern toxins, such as lead and antifreeze, to find out why they don t elicit a negative response from our taste buds. For more information on green chemistry, visit glencoe.com. 

Antifreezes function similarly when used as de-icing fluids for aircraft, airport runways, locks, and other applications. Here, the antifreeze melts the ice crystals by forming a mixture that freezes lower than the ambient temperatures. For aircraft de-icing and other critical applications, antifreezes are often concentrated glycols, water being considered too corrosive and flammable solvents too dangerous. 

A drawback of the liquid-type collectors is the danger of leakage and freezing. The former can be averted by appropriate junctions that permit dilatation, the latter by using antifreeze liquids as working media, for example, by integration into the hot water system of the farm for year-round performance. 

The coolant of fuel cells flows through a fuel cell stack and there is a danger of a short circuit of cells or a leakage of current if electrical conductivity of the coolant is high. Thus, ion exchanged water with an electrical conductivity of 1 mS or less, or a low-conductive antifreeze, is used as coolant. 

The most prevalent type of vaporizer for this purpose is the vertical bayonet. The main point to consider is whether there is a likelihood of damming or stoppage of the condensate inside the tube at a time when surrounding liquid is below 32°F (0°C). In that event, freezing is a danger and in such times, the antifreeze aspect of the vertical bayonet vaporizer becomes desirable. 

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